The brain organizes information about the sensory world into maps. Prominent examples are the maps of eye-preference and retinotopy in the lateral geniculate nucleus, superior colliculus and visual cortex. Experiments in this proposal will advance our understanding of mechanisms responsible for the development of precise neural circuitry in the mammalian brain. We will employ a broad range of techniques, including molecular biological, cell biological, neuroanatomical, electrophysiological and advanced optical imaging techniques in vitro and in vivo. We focus our experiments on maps of eye preference and retinotopy in the superior colliculus and lateral geniculate nucleus of the mouse. These structures are the dominant target of retinal projections to the brain. The lateral geniculate nucleus is the primary relay of visual information to the visual cortex, and the superior colliculu is a sensory motor structure that has emerged as an ideal model system for the examination of neural circuit development and function. It is widely hypothesized that molecular cues are responsible for the establishment of coarse map structure in the lateral geniculate and superior colliculus, and activity dependent processes subsequently refine these sensory motor circuits to functional precision. We first propose to definitively establish whether patterned spontaneous activity is necessary for the development of visual maps. We next propose to manipulate the temporal pattern of activity in the developing retina to examine the dependence of retinocollicular development of retinal ganglion cell activity. We finally propose to manipulate th spatial pattern of activity in the developing retina to examine the dependence of visual map development on the spatial character of spontaneous retinal activity. In all, the experiments in this proposal are designed to investigate the mechanisms responsible for the development of precise neural circuits in the mammalian brain, with a specific emphasis on the emergence of visual maps in the mouse superior colliculus.